Patent document CN102838550A discloses a quinazolin crotyl compound—a compound of formula I,

The compound of formula I has been proved to be the ideal and highly effective dual irreversible tyrosine kinase inhibitor, it can competitively bind to ATP by acting on the intracellular part of EGFR, inhibit the activation and phosphorylation of kinase, and block EGFR tyrosine kinase ATP binding sites so as to achieve the purpose of specific inhibition of EGFR. The compound can be used for the treatment or prevention of various indications related to EGFR and HER2 kinase function, comprising but are not limited to breast cancer, ovarian cancer, gastrointestinal cancer, esophageal cancer, lung cancer, head and neck squamous cell carcinoma, pancreatic cancer, epidermal squamous carcinoma, prostate cancer, glioma and nasopharyngeal carcinoma and other malignant tumor diseases.
The example 1 of the above-mentioned patent document also discloses a method for the synthesis of the compound of the above formula I, which provides a free base of the compound of formula I. The inventors have found that the long-term storage stability and the water solubility of the free base are poor, thus the free base is not ideal for use as drug substance for drug product preparations.
Accordingly, there is a need for drug substance of the compound of formula I having better physical properties and is suitable for use in pharmaceutical applications.